The present invention relates to a perpendicular recording magnetic head and a magnetic disk storage which incorporates the same.
In a magnetic disk storage, data on a recording medium is read or written by a magnetic head. In order to increase the magnetic disk's recording capacity per unit area, a higher areal density is needed. However, the current longitudinal recording method has a problem that as the write bit length decreases, it becomes difficult to increase the areal density due to thermal fluctuation in medium magnetization. A solution to this problem is a perpendicular recording method whereby magnetization signals are recorded in a direction perpendicular to the medium surface.
The perpendicular recording method is available in two types: one type uses a double-layered perpendicular medium having a soft under layer and the other type uses a single-layered perpendicular medium having no soft under layer. When a double-layered perpendicular medium is used as a recording medium, a stronger field can be applied to the medium by using a “single-pole head” which has a main pole and an auxiliary pole for recording.
FIG. 8 shows the relation between a perpendicular recording magnetic head 14 and a magnetic disk 11 and schematically illustrates how perpendicular recording takes place. A conventional magnetic head consists of a lower reader shield 8, a read element 7, an upper reader shield 9, an auxiliary pole 3, a thin film coil 2, and a main pole 1 which are laminated in the head traveling direction (from the leading side) in the order of mention. The lower reader shield 8, read element 7 and upper reader shield 9 constitute a read head 24 while the auxiliary pole 3, thin film coil 2 and main pole 1 constitute a write head (single-pole head) 25. Taking it into consideration that the head may have a skew angle, the air-bearing surface of the main pole is trapezoidal with its leading side width smaller than its trailing side one. A magnetic field from the main pole 1 of the write head 25 passes through a recording layer 19 and a soft under layer 20 of the magnetic disk 11 and enters the auxiliary pole 3 to make up a magnetic circuit so that a magnetization pattern is recorded on the recording layer 19. There may be an intermediate layer between the recording layer 19 and the soft under layer 20. The read element 7 of the read head 24 may be a giant magneto resistive element (GMR) or a tunneling magneto resistive element (TMR).